Formula Sheet
Every key formula of the course on one page, grouped by chapter, with a link back to the section that develops it.
Chapter 1 · Chemical Reactions and Equations
Law of conservation of mass§ 1.1 →
In a closed system (all gases counted): total mass of reactants $=$ total mass of products, e.g. $\mathrm{CaCO_{3}} \rightarrow \mathrm{CaO} + \mathrm{CO_{2}}$: $10.0\ \mathrm{g} \rightarrow 5.6\ \mathrm{g} + 4.4\ \mathrm{g}$
State symbols§ 1.1 →
$\mathrm{(s)}$ solid / precipitate · $\mathrm{(l)}$ liquid · $\mathrm{(g)}$ gas · $\mathrm{(aq)}$ dissolved in water
Burning magnesium§ 1.1 →
$\mathrm{2Mg(s) + O_{2}(g) \rightarrow 2MgO(s)}$ (dazzling white flame, white ash)
Iron and steam (balancing example)§ 1.1 →
$\mathrm{3Fe(s) + 4H_{2}O(g) \rightarrow Fe_{3}O_{4}(s) + 4H_{2}(g)}$
Yellow precipitate of lead iodide§ 1.1 →
$\mathrm{Pb(NO_{3})_{2}(aq) + 2KI(aq) \rightarrow PbI_{2}(s) + 2KNO_{3}(aq)}$
Zinc and dilute sulphuric acid§ 1.1 →
$\mathrm{Zn(s) + H_{2}SO_{4}(aq) \rightarrow ZnSO_{4}(aq) + H_{2}(g)}$ (flask warms, gas bubbles)
The four families of reactions§ 1.2 →
combination $\mathrm{A + B \rightarrow AB}$ · decomposition $\mathrm{AB \rightarrow A + B}$ · displacement $\mathrm{A + BC \rightarrow AC + B}$ · double displacement $\mathrm{AB + CD \rightarrow AD + CB}$
Quicklime, slaked lime and whitewash§ 1.2 →
$\mathrm{CaO(s) + H_{2}O(l) \rightarrow Ca(OH)_{2}(aq)}$ (exothermic) · on the wall: $\mathrm{Ca(OH)_{2}(aq) + CO_{2}(g) \rightarrow CaCO_{3}(s) + H_{2}O(l)}$
Thermal decompositions§ 1.2 →
$\mathrm{CaCO_{3} \rightarrow CaO + CO_{2}}$ · $\mathrm{2FeSO_{4} \rightarrow Fe_{2}O_{3} + SO_{2} + SO_{3}}$ · $\mathrm{2Pb(NO_{3})_{2} \rightarrow 2PbO + 4NO_{2} + O_{2}}$ (brown fumes) — all on heating
Electrolytic and photolytic decomposition§ 1.2 →
$\mathrm{2H_{2}O \xrightarrow{\text{current}} 2H_{2} + O_{2}}$ (volumes 2 : 1) · $\mathrm{2AgCl \xrightarrow{\text{sunlight}} 2Ag + Cl_{2}}$ (white → grey)
Displacement (more reactive metal wins)§ 1.2 →
$\mathrm{Fe(s) + CuSO_{4}(aq) \rightarrow FeSO_{4}(aq) + Cu(s)}$ — only if the free metal is above the other in K Na Ca Mg Al Zn Fe Pb Cu Hg Ag Au
Double displacement (white precipitate)§ 1.2 →
$\mathrm{Na_{2}SO_{4}(aq) + BaCl_{2}(aq) \rightarrow BaSO_{4}(s) + 2NaCl(aq)}$
Oxidation and reduction (Class 10 definitions)§ 1.3 →
oxidation = gain of O or loss of H · reduction = loss of O or gain of H · they always occur together (redox)
Oxidising and reducing agents§ 1.3 →
oxidising agent: gives O / takes H, is itself reduced · reducing agent: takes O / gives H, is itself oxidised
Copper oxide and hydrogen§ 1.3 →
$\mathrm{CuO(s) + H_{2}(g) \xrightarrow{\text{heat}} Cu(s) + H_{2}O(l)}$ — $\mathrm{CuO}$ reduced, $\mathrm{H_{2}}$ oxidised (black → reddish-brown)
More redox reactions§ 1.3 →
$\mathrm{ZnO + C \rightarrow Zn + CO}$ · $\mathrm{MnO_{2} + 4HCl \rightarrow MnCl_{2} + 2H_{2}O + Cl_{2}}$
Rusting of iron (needs oxygen and water)§ 1.3 →
$\mathrm{4Fe(s) + 3O_{2}(g) + 2xH_{2}O(l) \rightarrow 2Fe_{2}O_{3}\cdot xH_{2}O(s)}$
Preventing rancidity§ 1.3 →
antioxidants · airtight containers · nitrogen-flushed packets · refrigeration · keep away from light
Chapter 2 · Acids, Bases and Salts
Indicator colours (acid · neutral · base)§ 2.1 →
litmus: red · purple · blue — phenolphthalein: colourless · colourless · pink — methyl orange: red · yellow · yellow — turmeric: yellow · yellow · reddish-brown — onion / vanilla / clove: smell lost only in bases
Acid + metal → salt + hydrogen (pop test)§ 2.1 →
$\mathrm{Zn(s) + H_{2}SO_{4}(aq) \rightarrow ZnSO_{4}(aq) + H_{2}(g)}$ · active metals only (not Cu, Ag) · also $\mathrm{Zn + 2NaOH \rightarrow Na_{2}ZnO_{2} + H_{2}}$
Carbonate / hydrogencarbonate + acid → salt + CO₂ + water§ 2.1 →
$\mathrm{Na_{2}CO_{3} + 2HCl \rightarrow 2NaCl + H_{2}O + CO_{2}}$ · $\mathrm{NaHCO_{3} + HCl \rightarrow NaCl + H_{2}O + CO_{2}}$
Lime water test for CO₂§ 2.1 →
$\mathrm{Ca(OH)_{2} + CO_{2} \rightarrow CaCO_{3} + H_{2}O}$ (milky) · excess: $\mathrm{CaCO_{3} + H_{2}O + CO_{2} \rightarrow Ca(HCO_{3})_{2}}$ (clear)
Neutralisation§ 2.1 →
base + acid → salt + water · $\mathrm{H^{+}(aq) + OH^{-}(aq) \rightarrow H_{2}O(l)}$
Oxides and ions§ 2.1 →
metal oxides basic, non-metal oxides acidic · acids give $\mathrm{H^{+}}$ ($\mathrm{H_{3}O^{+}}$), alkalis give $\mathrm{OH^{-}}$ · add acid to water
pH scale and universal indicator§ 2.2 →
pH $\lt 7$ acidic · pH $=7$ neutral · pH $\gt 7$ basic · red (0–2) · orange (3–4) · yellow (5–6) · green (7) · blue (8–9) · indigo (10–11) · violet (12–14)
Strong and weak acids§ 2.2 →
$\mathrm{HCl(aq) \rightarrow H^{+}(aq) + Cl^{-}(aq)}$ (strong, complete) · $\mathrm{CH_{3}COOH(aq) \rightleftharpoons H^{+}(aq) + CH_{3}COO^{-}(aq)}$ (weak, partial)
Dilution§ 2.2 →
acid + water: pH rises towards 7, never above · base + water: pH falls towards 7, never below
Key pH values§ 2.2 →
stomach 1.5–3.0 · blood 7.35–7.45 · tooth decay below 5.5 · acid rain below 5.6 · most crops 6–7.5
Acid rain§ 2.2 →
$\mathrm{2SO_{2} + O_{2} + 2H_{2}O \rightarrow 2H_{2}SO_{4}}$ · $\mathrm{4NO_{2} + O_{2} + 2H_{2}O \rightarrow 4HNO_{3}}$
pH of a salt solution§ 2.3 →
strong acid + strong base: neutral (NaCl) · strong acid + weak base: acidic ($\mathrm{NH_{4}Cl}$, $\mathrm{CuSO_{4}}$) · weak acid + strong base: basic ($\mathrm{Na_{2}CO_{3}}$, $\mathrm{CH_{3}COONa}$)
Chlor-alkali process§ 2.3 →
$\mathrm{2NaCl(aq) + 2H_{2}O(l) \rightarrow 2NaOH(aq) + Cl_{2}(g) + H_{2}(g)}$ · $\mathrm{Cl_{2}}$ at anode, $\mathrm{H_{2}}$ at cathode
Baking soda§ 2.3 →
$\mathrm{NaCl + H_{2}O + CO_{2} + NH_{3} \rightarrow NH_{4}Cl + NaHCO_{3}}$ · $\mathrm{2NaHCO_{3} \xrightarrow{\text{heat}} Na_{2}CO_{3} + H_{2}O + CO_{2}}$
Washing soda§ 2.3 →
$\mathrm{Na_{2}CO_{3}\cdot 10H_{2}O}$ · from $\mathrm{Na_{2}CO_{3} + 10H_{2}O}$
Bleaching powder§ 2.3 →
$\mathrm{Cl_{2} + Ca(OH)_{2} \rightarrow CaOCl_{2} + H_{2}O}$
Plaster of Paris and water of crystallisation§ 2.3 →
$\mathrm{CaSO_{4}\cdot 2H_{2}O \xrightarrow{373\ K} CaSO_{4}\cdot\tfrac{1}{2}H_{2}O + 1\tfrac{1}{2}H_{2}O}$ · $\mathrm{CuSO_{4}\cdot 5H_{2}O \xrightarrow{\text{heat}} CuSO_{4} + 5H_{2}O}$ (blue → white)
Chapter 3 · Metals and Non-metals
The reactivity series§ 3.1 →
K > Na > Ca > Mg > Al > Zn > Fe > Pb > [H] > Cu > Hg > Ag > Au (most reactive → least reactive)
Metals and non-metals with oxygen§ 3.1 →
metal + O₂ → basic oxide (Al₂O₃, ZnO amphoteric) · non-metal + O₂ → acidic / neutral oxide · $\mathrm{4Al + 3O_{2} \rightarrow 2Al_{2}O_{3}}$
Metals with water§ 3.1 →
$\mathrm{2Na + 2H_{2}O \rightarrow 2NaOH + H_{2}}$ · $\mathrm{3Fe + 4H_{2}O(g) \rightarrow Fe_{3}O_{4} + 4H_{2}}$ · Al, Zn, Fe need steam; Cu, Ag, Au none
Metals with dilute acids; aqua regia§ 3.1 →
metal + dilute acid → salt + H₂ (metals above H only) · no H₂ with HNO₃ (except Mg, Mn) · aqua regia = 3 conc. HCl : 1 conc. HNO₃
Displacement of a metal from its salt§ 3.1 →
$\mathrm{Fe(s) + Cu^{2+}(aq) \rightarrow Fe^{2+}(aq) + Cu(s)}$ · only a more reactive metal displaces a less reactive one
Electron arrangements (K, L, M, N)§ 3.2 →
Li 2,1 · O 2,6 · F 2,7 · Ne 2,8 · Na 2,8,1 · Mg 2,8,2 · Al 2,8,3 · Cl 2,8,7 · Ar 2,8,8 · Ca 2,8,8,2
Forming ions§ 3.2 →
$\mathrm{Na \rightarrow Na^{+} + e^{-}}$ · $\mathrm{Mg \rightarrow Mg^{2+} + 2e^{-}}$ · $\mathrm{Cl + e^{-} \rightarrow Cl^{-}}$ · $\mathrm{O + 2e^{-} \rightarrow O^{2-}}$ — metals lose, non-metals gain
Formula from charge balance§ 3.2 →
$\mathrm{NaCl}$ ($+1,-1$) · $\mathrm{MgCl_{2}}$ ($+2,2\times-1$) · $\mathrm{MgO}$ ($+2,-2$) · $\mathrm{Al_{2}O_{3}}$ ($2\times+3,3\times-2$) · total charge $=0$
Properties of ionic compounds§ 3.2 →
hard, brittle crystals · high melting points ($\mathrm{NaCl}$ $1074\ \mathrm{K}$) · soluble in water, not in kerosene · conduct when molten or dissolved, not as solids
Extraction method by reactivity§ 3.3 →
K, Na, Ca, Mg, Al: electrolysis of molten compound · Zn, Fe, Pb: oxide + carbon · Cu, Hg: heat sulphide in air · Ag, Au: found free
Roasting, calcination, reduction (zinc)§ 3.3 →
$\mathrm{2ZnS + 3O_{2} \rightarrow 2ZnO + 2SO_{2}}$ · $\mathrm{ZnCO_{3} \rightarrow ZnO + CO_{2}}$ · $\mathrm{ZnO + C \rightarrow Zn + CO}$
Metals low in the series§ 3.3 →
$\mathrm{2HgS + 3O_{2} \rightarrow 2HgO + 2SO_{2}}$ · $\mathrm{2HgO \rightarrow 2Hg + O_{2}}$ · $\mathrm{2Cu_{2}S + 3O_{2} \rightarrow 2Cu_{2}O + 2SO_{2}}$ · $\mathrm{2Cu_{2}O + Cu_{2}S \rightarrow 6Cu + SO_{2}}$
Thermite reaction§ 3.3 →
$\mathrm{Fe_{2}O_{3} + 2Al \rightarrow Al_{2}O_{3} + 2Fe}$ (molten iron, heat) · $\mathrm{3MnO_{2} + 4Al \rightarrow 3Mn + 2Al_{2}O_{3}}$
Electrolytic reduction§ 3.3 →
cathode: $\mathrm{Na^{+} + e^{-} \rightarrow Na}$ · anode: $\mathrm{2Cl^{-} \rightarrow Cl_{2} + 2e^{-}}$ · $\mathrm{2NaCl(l) \rightarrow 2Na(l) + Cl_{2}(g)}$ · $\mathrm{2Al_{2}O_{3} \rightarrow 4Al + 3O_{2}}$
Electrolytic refining of copper§ 3.3 →
anode (impure): $\mathrm{Cu \rightarrow Cu^{2+} + 2e^{-}}$ · cathode (pure): $\mathrm{Cu^{2+} + 2e^{-} \rightarrow Cu}$ · electrolyte: acidified $\mathrm{CuSO_{4}}$
Corrosion, protection and alloys§ 3.3 →
rust $\mathrm{Fe_{2}O_{3}\cdot xH_{2}O}$ · $\mathrm{4Ag + 2H_{2}S + O_{2} \rightarrow 2Ag_{2}S + 2H_{2}O}$ · galvanising (zinc) · steel Fe+C · brass Cu+Zn · bronze Cu+Sn · solder Pb+Sn · $22$-carat gold $=\tfrac{22}{24}=91.7\%$ gold
Chapter 4 · Carbon and its Compounds
Shared pairs from valency§ 4.1 →
bonds formed $=$ electrons needed: $\mathrm{H}$ 1 · $\mathrm{Cl}$ 1 · $\mathrm{O}$ 2 · $\mathrm{N}$ 3 · $\mathrm{C}$ 4 (shared pair counts for both atoms)
Single, double and triple bonds§ 4.1 →
H–H · Cl–Cl (single) · O=O · O=C=O (double) · N≡N (triple) · $\mathrm{CH_{4}}$: four C–H · $\mathrm{H_{2}O}$: H–O–H
Check an electron-dot structure§ 4.1 →
$2\times(\text{shared pairs}) + 2\times(\text{lone pairs}) = $ total outer electrons; e.g. $\mathrm{CO_{2}}$: $8+8=4+6+6=16$
Properties of covalent compounds§ 4.1 →
low melting and boiling points · poor electrical conductors · mostly insoluble in water (soluble in organic solvents) — exceptions: diamond, graphite
Allotropes of carbon§ 4.1 →
diamond: 4 bonds per C, hardest, insulator · graphite: 3 bonds per C, layers, conducts · $\mathrm{C_{60}}$: 3 bonds per C, 20 hexagons $+$ 12 pentagons, mass $720\ \mathrm{u}$
General formulas of hydrocarbons§ 4.2 →
alkanes $\mathrm{C_{n}H_{2n+2}}$ (single bonds) · alkenes $\mathrm{C_{n}H_{2n}}$ (one C=C) · alkynes $\mathrm{C_{n}H_{2n-2}}$ (one C≡C)
Word roots for the carbon chain§ 4.2 →
1 meth · 2 eth · 3 prop · 4 but · 5 pent · 6 hex — ending -ane (single), -ene (double), -yne (triple)
Functional groups and IUPAC endings§ 4.2 →
halo: chloro-/bromo- (prefix) · $-\mathrm{OH}$ -ol · $-\mathrm{CHO}$ -al · $>\mathrm{C{=}O}$ -one · $-\mathrm{COOH}$ -oic acid · C=C -ene · C≡C -yne
Homologous series§ 4.2 →
successive members differ by $\mathrm{CH_{2}}=14\ \mathrm{u}$ · alcohols $\mathrm{C_{n}H_{2n+1}OH}$ · carboxylic acids $\mathrm{C_{n}H_{2n+1}COOH}$
Three-carbon compounds§ 4.2 →
chloropropane $\mathrm{C_{3}H_{7}Cl}$ · propanol $\mathrm{C_{3}H_{7}OH}$ · propanal $\mathrm{C_{2}H_{5}CHO}$ · propanone $\mathrm{CH_{3}COCH_{3}}$ · propanoic acid $\mathrm{C_{2}H_{5}COOH}$ · propene $\mathrm{C_{3}H_{6}}$ · propyne $\mathrm{C_{3}H_{4}}$
Complete combustion§ 4.3 →
$\mathrm{CH_{4} + 2O_{2} \rightarrow CO_{2} + 2H_{2}O}$ · $\mathrm{C_{2}H_{5}OH + 3O_{2} \rightarrow 2CO_{2} + 3H_{2}O}$ · $\mathrm{C_{3}H_{8} + 5O_{2} \rightarrow 3CO_{2} + 4H_{2}O}$ · $\mathrm{2C_{2}H_{2} + 5O_{2} \rightarrow 4CO_{2} + 2H_{2}O}$
Flames and carbon content§ 4.3 →
saturated (clean, blue flame): $\mathrm{CH_{4}}$ 75.0 % C · $\mathrm{C_{2}H_{6}}$ 80.0 % C — unsaturated (yellow, sooty): $\mathrm{C_{2}H_{4}}$ 85.7 % C · $\mathrm{C_{2}H_{2}}$ 92.3 % C
Oxidation of ethanol§ 4.3 →
$\mathrm{CH_{3}CH_{2}OH + 2[O] \xrightarrow{\text{alk. KMnO}_{4}\ \text{or acid. K}_{2}\text{Cr}_{2}\text{O}_{7}} CH_{3}COOH + H_{2}O}$
Addition (hydrogenation)§ 4.3 →
$\mathrm{CH_{2}{=}CH_{2} + H_{2} \xrightarrow{\text{Ni}} CH_{3}CH_{3}}$ · $\mathrm{HC{\equiv}CH + 2H_{2} \xrightarrow{\text{Ni}} CH_{3}CH_{3}}$ · vegetable oil $\xrightarrow{\text{H}_{2},\ \text{Ni}}$ vanaspati ghee
Substitution (chlorination)§ 4.3 →
$\mathrm{CH_{4} + Cl_{2} \xrightarrow{\text{sunlight}} CH_{3}Cl + HCl}$ — then $\mathrm{CH_{2}Cl_{2}}$, $\mathrm{CHCl_{3}}$, $\mathrm{CCl_{4}}$
Reactions of ethanol§ 4.4 →
$\mathrm{2C_{2}H_{5}OH + 2Na \rightarrow 2C_{2}H_{5}ONa + H_{2}}$ · $\mathrm{C_{2}H_{5}OH \xrightarrow[443\ K]{\text{conc. H}_{2}\text{SO}_{4}} C_{2}H_{4} + H_{2}O}$ · b.p. $351\ \mathrm{K}$
Reactions of ethanoic acid§ 4.4 →
$\mathrm{CH_{3}COOH + NaOH \rightarrow CH_{3}COONa + H_{2}O}$ · $\mathrm{2CH_{3}COOH + Na_{2}CO_{3} \rightarrow 2CH_{3}COONa + H_{2}O + CO_{2}}$ · $\mathrm{CH_{3}COOH + NaHCO_{3} \rightarrow CH_{3}COONa + H_{2}O + CO_{2}}$
Esterification and saponification§ 4.4 →
$\mathrm{CH_{3}COOH + C_{2}H_{5}OH \rightleftharpoons CH_{3}COOC_{2}H_{5} + H_{2}O}$ (conc. $\mathrm{H_{2}SO_{4}}$) · $\mathrm{CH_{3}COOC_{2}H_{5} + NaOH \rightarrow CH_{3}COONa + C_{2}H_{5}OH}$
Making soap§ 4.4 →
fat $+$ 3 NaOH $\rightarrow$ 3 soap $+$ glycerol: $\mathrm{(C_{17}H_{35}COO)_{3}C_{3}H_{5} + 3NaOH \rightarrow 3C_{17}H_{35}COONa + C_{3}H_{5}(OH)_{3}}$
Soap, micelle, scum and detergent§ 4.4 →
soap $=\mathrm{C_{17}H_{35}COO^{-}Na^{+}}$ (tail in oil, head in water) · $\mathrm{2C_{17}H_{35}COONa + CaCl_{2} \rightarrow (C_{17}H_{35}COO)_{2}Ca\downarrow + 2NaCl}$ · detergent Ca/Mg salts are soluble